Question

A student placed 16.0 g of glucose (C6H12O6) in a volumetric flask, added enough water to dissolve the glucose by swirling, then carefully added additional water until the 100.ml mark on the neck of the flask was reached. The flask was then shaken until the solution was uniform. A 55.0 ml sample of this glucose solution was diluted to 0.500 L . How many grams of glucose are in 100 ml. of the final solution?
Express your answer numerically in grams.

Answer 1

So we'll start of by converting our original weight to mols.
1.=.08889 mols

Now we need to calculate the molarity of the solution that is made. Remember that molarity is mols/Liter

2. .08889 mol/100E-3 L=.88889 M

Taking out 55 mL, we need to calculate the number of mols in 55 mL of this solution

3. .055 L x (.8889 mol/1 L)=.048889 mol

Again, we calculate the molarity of the new solution by dividing the number of mols by the new total volume

4. .048889 mol/.5 L=.097778 M

Then to find out the number of grams in 100 mL of this solution we calculate the number of mols, then convert that to grams of glucose.

5. .1 L x (.097778 mol/1 L)=.0097778 mol

.097778 mol x (180 g/1 mol)=1.76 grams of glucose